1. Field
Apparatuses consistent with exemplary embodiments relate to a light apparatus of a chip mounter, and more particularly, to a side light apparatus of a chip mounter, in which each light source emits light to a side surface of not a spindle or nozzle located directly in front thereof but a spindle or nozzle located obliquely thereto in order to provide optimal lighting in a narrow space.
2. Description of the Related Art
With the development of electronic and communication technology, various electronic devices are becoming smaller and lighter. Accordingly, it is essential to make electronic parts (such as semiconductor chips) embedded in the various electronic devices highly integrated and ultra-small.
Small electronic parts are mounted on a printed circuit board (PCB) by a part mounter such as a chip mounter. There are thousands of types of electronic parts that can be mounted on a PCB by a chip mounter. Due to the high integration density and ultra-small size of such electronic parts, it is required to develop inspection and measurement technology for determining whether the electronic parts have been picked up and mounted on a PCB accurately.
To this end, various functions for ensuring the part-mounting quality of a chip mounter are being implemented. In particular, various methods of inspecting the picked-up state of a part to find a possible defect state in advance and enable accurate mounting are being implemented. These methods are broadly divided into two types: one is methods using pneumatic pressure and the other is methods using images.
The methods using pneumatic pressure suffer from a high frequency of false defects due to the state of nozzles, whether parts have been picked up by the nozzles, and the instability of reference pneumatic pressure. Therefore, the methods using images are preferred. In a related art method using images, an image capture device is placed directly under a nozzle to capture an image of the nozzle and determines whether a part has actually been picked up by the nozzle using the captured image of the nozzle. To clearly capture the image of the part, light is projected onto the part.
To accurately recognize edge lines of parts, part mounting equipment mostly emits light from sides of the parts. In particular, to recognize parts with round or sphere edges (not sharp edges), the part mounting equipment forms a circular or square shape around a focus at which a part is to be recognized and emits light to the part, thereby revealing edges of the part.
FIG. 1A is a diagram illustrating an example part picked up by a chip mounter. FIG. 1B is a diagram illustrating a related art chip mounter which captures an image of a part picked up by a nozzle using a camera. FIG. 1C is a diagram illustrating a related art light apparatus which emits light to a picked-up part. FIG. 1D shows an image of a part captured by the camera.
An ultra-small part such as a flipchip does not have leads but has a plurality of protrusions called “balls.” Referring to FIG. 1A, a part 5 includes a plurality of balls 6. The part 5 is picked up by a chip mounter and mounted on a PCB.
Referring to FIG. 1B, a head 10 of the chip mounter includes one or more nozzles 12 which pick up parts 5. The head 10 may be circular or square. To pick up the parts 5, the head 10 may move vertically and horizontally while rotating. The nozzles 12 may be arranged at regular intervals in the head 10, supported respectively by spindles 11, and connected to the head 10. A camera 20 is placed on a side of or under the head 10 and captures an image of a side surface or a bottom surface of a part 5 and a spindle 11. Then, the camera 20 analyzes the captured image of the part 5 and obtains information about the length, width, twisted angle and position of the part 5.
After the part 5 is picked up, light should be projected not only onto a top or bottom surface of the part 5 but also to side surfaces of the part 5. Only then can balls 6 located on the bottom surface of the part 5 be clearly “vision-recognized,” and thus edges of the part 5 can be recognized clearly. Here, “vision recognition” is to capture and obtain an image of the part 5 using the camera 20 or display an image of the part 5 seen through a lens. Vision recognition is a concept corresponding to the recognition of an object with human eyes.
Therefore, for accurate recognition of edge lines of the part 5, light is projected not only onto the top and bottom surfaces of the part 5 but also onto the side surfaces of the part 5. Referring to FIG. 1C, a top light source 31 and a bottom light source 33 are placed above and under the part 5 to emit light to the top and bottom surfaces of the part 5. In addition, side light sources 35-1 and 35-2 are located on left and right sides of the part 5 to emit light to both side surfaces of the part 5, respectively. Accordingly, not only the edges of the part 5 but also the balls 6 of the part 5 can be recognized accurately.
Referring to FIG. 1D, when the part 5 is located at the focus of the camera 20, if light is projected onto the side surfaces of the part 5, an image in which the balls 6 of the part 5 look like donuts can be obtained. Also, the presence or absence of the balls 6 of the part 5 can be identified in the image.
To increase the speed of part mounting equipment such as a chip mounter and reduce the weight of the chip mounter, the gap between spindles 11 of a head 10 of the chip mounter is being reduced, and more spindles 11 are being arranged in an outer region of the head 10. In this structure, however, side lights cannot be arranged in a row or a circular shape due to the limited space in which the side lights for accurately recognizing the edges of parts 5 are installed.
For example, if the side lights are arranged in a row, the size of a region where the parts 5 are to be mounted may be reduced. In addition, if one recognition device (e.g., a camera) recognizes each part 5 of the head 10 one by one, there is no problem with light uniformity. However, if the recognition device recognizes two or more parts 5, a part 5 on the left or right side of a spindle 11 at each end of the head 10, that is, the outermost part 5 may appear dark due to the interference between the side lights.